JP2014056127A - Spacer, spacer aggregate, wafer level package structure, and manufacturing method of spacer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spacer capable of intercepting light from a side direction of a wafer level package structure, and suppressing an influence of scattered light inside the wafer level package structure.SOLUTION: A spacer for wafer level package structure is made of ceramic materials containing an optical absorption material except a glass material.

Description

  The present invention relates to a spacer, a spacer assembly, a wafer level package structure, and a method for manufacturing the spacer, and more particularly, a spacer used in a wafer level package structure, a spacer assembly having the spacer, and a wafer level package structure. And a method for manufacturing the spacer.

  In recent years, a wafer level package has been used as an electronic component package for sealing an electronic component such as an image sensor or a MEMS (Micro Electro Mechanical Systems) device. The wafer level package is manufactured at the wafer level, and a sealing process or the like is performed at the wafer level before dicing. The wafer level package is mounted on the mounting substrate in a state where other structures are stacked in addition to being mounted on the mounting substrate alone.

  In the case of an image pickup apparatus in which an image pickup device that is one type of wafer level package is sealed, for example, a lens unit having a plurality of lens elements is arranged on the light receiving surface side, and is mounted on a mounting substrate as a wafer level camera module (WLCM). Implemented. As a lens unit, for example, a lens unit that supports and fixes the side portions of a plurality of lens elements, and a lens unit that fixes and arranges spacers between the plurality of lens elements are known (for example, Patent Document 1). reference). As the spacer, for example, a spacer made of a glass wafer is known (see Non-Patent Document 1, for example).

  Among these, the lens unit using a spacer is manufactured as follows, for example. First, using a glass wafer having a plurality of regions to be lens elements, that is, a plurality of regions corresponding to the imaging device, a lens portion is formed with a plastic material or the like in each region, and a lens element assembly (lens element wafer) Manufacturing. In addition, a spacer assembly (spacer wafer) is manufactured by forming through holes so as to correspond to the respective regions using another glass wafer having the same size as the glass wafer. These lens element assemblies and spacer assemblies are laminated in a predetermined order to form a lens unit assembly (lens unit wafer). Further, the lens unit assembly is diced to produce a plurality of lens units. Then, a wafer level camera module is manufactured by laminating a lens unit on the imaging device.

JP 2010-11230 A (FIG. 3)

Romain Fraux, "OmniVision's VGA wafer-level camera", [online], 3D packaging, Yole Developpement, FEBRUARY 2012, ISSUE No22, p.26-27, Internet <URL: http://www.bluetoad.com/publication/ ? i = 100874>

  In the imaging apparatus as described above, the light from the subject is converged on the light receiving surface of the image sensor by the lens, and the image signal is output based on the light receiving signal corresponding to the light amount on the light receiving surface.

However, in such an imaging apparatus, when light from the subject is received by the lens, the light may leak from a direction other than the front of the lens, that is, from the side surface of the lens unit. In this case, incident light from the side surface of the lens unit travels in the lens unit without being converged by the lens. Therefore, when such incident light reaches the light receiving surface of the image sensor, the sharpness of the captured image is increased. It may be damaged to cause problems such as image blur.
In addition, even when the light is incident from the front direction of the lens, for example, when entering the lens unit without being refracted due to a small incident angle with respect to the light receiving surface of the lens, or when there is a minute distortion in the lens, Scattered light may be generated in the lens unit. Even when such scattered light reaches the light receiving surface of the image sensor, the sharpness of the obtained image is impaired.

  In order to solve such a problem, for example, Patent Document 1 proposes a camera module in which the side surface of the entire camera module including the solid-state imaging device 10 and the lens unit 20 is covered with the metal deposition film 1. .

  However, in this case, after assembling the entire camera module, a process of providing a metal vapor deposition film or the like on the entire side surface is required, so that the manufacturing process becomes complicated.

  In addition, as a technique for providing light shielding properties inside the hole of the lens unit, it is also possible to apply a light shielding film using a black paste or silver paste on the surface inside the hole in the manner of through-hole printing. . However, this method complicates the manufacturing process, and through-hole printing makes it difficult to control the printed film thickness, and it is difficult to stably produce within the required hole diameter tolerance. It has not been put into practical use as a method for producing a spacer having a spacer.

The present invention has been made to solve the above-described problems, and is a spacer used in a wafer level package structure, which can block light from the side surface and also scattered light inside the wafer level package structure. The purpose of the present invention is to provide a spacer that can suppress the influence of the above.
Another object of the present invention is to provide a spacer assembly which is an assembly of such spacers. Furthermore, the present invention aims to provide a wafer level package structure using such a spacer. Moreover, this invention aims at provision of the manufacturing method of such a spacer.

The spacer of the present invention is a spacer for a wafer level package structure, and is characterized by being made of a ceramic material other than a glass material containing a light absorbing material.
The wafer level package structure to which the spacer of the present invention is applied is not limited as long as it has at least the wafer level package, and may be composed of only the wafer level package, or other units are laminated on the wafer level package. It may be. The spacer of the present invention may be used for a wafer level package part of such a wafer level package structure or may be used for a unit part.

  The spacer assembly of the present invention is characterized in that a plurality of the spacers of the present invention are combined.

  The wafer level package structure of the present invention has at least a wafer level package and a spacer that forms a gap inside or outside the wafer level package, and has the spacer of the present invention as the spacer. Features.

  The spacer manufacturing method of the present invention is a sheet manufacturing process for manufacturing a ceramic green sheet comprising a light absorbing material, made of a ceramic material other than a glass material, and having a plurality of regions serving as spacers for a wafer level package structure. And a hole forming step of forming a through hole in the region, and a baking step of baking the ceramic green sheet to form a spacer aggregate.

  The spacer of this invention consists of ceramic materials other than glass material containing a light absorption material. According to the spacer of the present invention, light from the side surface can be blocked and scattered light inside the wafer level package structure can be absorbed. Therefore, for example, when applied to an imaging apparatus having a lens unit, the influence of light other than the convergent light by the lens can be suppressed, and a clear image without image blur can be obtained.

  In addition, since the spacer of the present invention is made of a ceramic material other than a glass material containing a light absorbing material, for example, a step of covering the spacer surface with a colored member such as a black member is not required. The work process when manufacturing the level package structure can be simplified.

  According to the spacer assembly of the present invention, a plurality of the spacers of the present invention are joined together, so that the spacer of the present invention can be produced efficiently.

  According to the wafer level package structure of the present invention, since the spacer of the present invention is provided, for example, when applied to a wafer level camera module, light from the side is blocked and scattering inside the wafer level package structure is also achieved. The influence of light is suppressed, and a clear image without image blur can be obtained.

  According to the manufacturing method of the present invention, a spacer capable of blocking light from the side surface direction of the wafer level package structure and suppressing the influence of scattered light inside the wafer level package structure by having a predetermined process. can do.

Sectional drawing which shows typically one Embodiment of a wafer level package structure. Sectional drawing which shows the state in which light injects into the wafer level package structure of FIG. Sectional drawing which shows typically one Embodiment of a spacer. Sectional drawing which shows other embodiment of a spacer typically. The top view which shows the green sheet used for manufacture of a spacer. The top view which shows the green sheet provided with the through-hole. The top view which shows the green sheet processed into the circular shape. Sectional drawing which shows one Embodiment of the manufacturing method of a wafer level package structure. It is a figure which shows the spectral reflectance of the spacer aggregate | assembly of Example 1. FIG.

Hereinafter, embodiments of the present invention will be described.
First, the example which applied the spacer of embodiment to the lens unit part of the wafer level camera module which is one Embodiment of a wafer level package structure is demonstrated. Hereinafter, the wafer level camera module is simply referred to as a camera module.

  FIG. 1 is a cross-sectional view showing the camera module 10. The camera module 10 includes an imaging device 11 as a wafer level package and a lens unit 12 disposed on the light receiving surface side of the imaging device 11.

  The imaging device 11 has, for example, a wafer level having an element substrate 13, a sealing substrate 14 made of a transparent substrate or the like disposed so as to face the element substrate 13, and a light receiving element 15 sealed therebetween. Chip size package. The element substrate 13 and the sealing substrate 14 are bonded together by an adhesive layer 16 disposed so as to surround the light receiving element 15. The light receiving element 15 is hermetically sealed by the element substrate 13, the sealing substrate 14, and the adhesive layer 16.

  For example, a plurality of electrode pads 17 are arranged on the surface of the element substrate 13 so as to surround the light receiving element 15. A peripheral circuit (not shown) is formed between the light receiving element 15 and the electrode pad 17. The electrode pad 17 is connected to the light receiving element 15 and its peripheral circuit by wiring, and is used for external connection for inputting an electric signal to the light receiving element 15 and its peripheral circuit, or for taking out an electric signal output from them. It is a pad.

  The light receiving element 15 is, for example, a solid-state imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). For example, a color filter (not shown) is provided on the light receiving surface of the light receiving element 15. In the light receiving element 15, exposure and light reception signal are read out in accordance with the electric signal input through the electrode pad 17, and the read light reception signal is output to the outside through the electrode pad 17.

  A plurality of solder balls 18 are disposed on the back side of the element substrate 13. The solder ball 18 functions as an external connection terminal for mounting on a mounting board such as a printed board, and is made of, for example, lead-free high melting point solder such as Sn-Ag-Cu. The position of the solder ball 18 is appropriately set according to the position of the bonding pad on the mounting substrate side. Thereby, the arrangement of the electrode pads 17 is converted into the arrangement of the solder balls 18 and can be directly mounted on the mounting board.

  A through via 19 is provided in the element substrate 13 at a position corresponding to the electrode pad 17. The through via penetrates from the front surface to the back surface of the element substrate 13. A wiring layer 21 is formed at the end of the through via 19 on the back side so as to cover the surface. Further, the wiring layer 21 is formed in a formation region that is a region where the solder balls 18 are formed.

  For example, the lens unit 12 is bonded to the light receiving surface side of the imaging device 11 by an adhesive layer (not shown). In the lens unit 12, for example, a plate-like lens element 22 and another plate-like lens element 23 are arranged to face each other via a spacer 24. The spacer 24 has a cylindrical shape, and the inside is a gap (hereinafter referred to as a gap S). This spacer 24 is made of the spacer of the embodiment, and is made of a ceramic material other than a glass material containing a light absorbing material. The lens element 22 and the spacer 24 and the lens element 23 and the spacer 24 are joined by an adhesive layer (not shown).

  For example, the lens element 22 has a lens portion 222 formed on the surface of a transparent substrate 221 such as a glass substrate. Similarly, the lens element 23 has a lens portion 232 formed on the surface of a transparent substrate 231 such as a glass substrate. For example, the spacer 24 is provided between the transparent substrate 221 and the transparent substrate 231 so as to surround the lens unit 222 and the lens unit 232. The lens unit 12 is further provided with a filter element 25 in which an infrared filter 252 is formed on the surface of a transparent substrate 251 such as a glass substrate, and a light shielding member 26 except for a portion where light enters.

  As described above, the spacer 24 is made of a ceramic material other than a glass material and contains a light absorbing material.

  The spacer 24 is a ceramic material other than a glass material and is not particularly limited as long as it contains a light absorbing material, but a black body is preferable from the viewpoint of obtaining good light shielding properties and light absorbing properties.

  Since the spacer 24 is made of a ceramic material other than a glass material and contains a light absorbing material, light from the side surface of the lens unit 12 to the inside of the lens unit 12, that is, the gap S, as shown in FIG. L1 leakage can be blocked. In addition, when the spacer 24 includes a light absorbing material, the spacer 24 can absorb light L2 that is not converged by the lens portion 232 and generates scattered light in the gap portion S, as shown in FIG. For this reason, the amount of the light L1 emitted from the side surface of the lens unit 12 toward the lens unit 12 and the scattered light in the gap S reaches the light receiving surface of the light receiving element 15 can be significantly reduced. For this reason, it is possible to suppress a decrease in image quality due to image blur or the like.

The visible light reflectance of the spacer 24 is preferably 30% or less.
When the visible light reflectance of the spacer 24 exceeds 30%, the scattered light in the gap S and the light incident on the gap S without passing through the lens portion 232 are not sufficiently absorbed by the spacer 24, and these scattering There is a possibility that light or the like cannot sufficiently be prevented from reaching the light receiving surface of the light receiving element 15. The visible light reflectance of the spacer 24 is more preferably 25% or less, and more preferably 20% or less.

Representative examples of the ceramic material other than the glass material include alumina ceramics, aluminum nitride ceramics, silicon nitride ceramics, silicon carbide ceramics, and glass ceramics.
Glass ceramics include those obtained by mixing and sintering glass powder and ceramic powder.

  By using a ceramic material other than the glass material, for example, when mixed with a black pigment, which will be described later, as the light absorbing material, the spacer 24 having good light shielding properties and light absorbing properties can be obtained.

  The three-point bending strength of a general glass material is about 55 MPa, but the three-point bending strength of ceramic materials other than the glass material is higher than this, so it is used for manufacturing the spacer 24 or such a spacer 24. Damage to the spacer assembly can be suppressed. Further, as can be seen from FIG. 1, since the spacer has the smallest cross-sectional area in the structure, increasing the strength of the spacer also contributes to increasing the strength of the entire package.

  Among the ceramic materials other than the glass material, in particular, a ceramic substrate that undergoes a green sheet process can easily form a through hole that becomes a void portion of the spacer 24 by punching at the stage of the ceramic green sheet before firing. Further, by performing punching at the stage of the ceramic green sheet, basically a through hole can be formed regardless of the thickness of the ceramic green sheet. Furthermore, it is easy to suppress the occurrence of an excessively small diameter of the through hole, and it is also easy to suppress the occurrence of minute convex portions such as burrs around the opening of the through hole. Here, “reducing the diameter” means that, for example, in a method of performing sandblasting or etching on a glass wafer, the hole diameter gradually decreases in the depth direction of the through hole.

  As ceramic materials other than the glass material, alumina ceramics and glass ceramics are preferable from the viewpoint of productivity and the like, and glass ceramics are particularly preferable from the viewpoint of productivity and the like. In other words, glass ceramics are obtained by dispersing ceramic particles in a glass matrix, and can lower the firing temperature compared to high-temperature fired ceramics such as alumina ceramics. In addition, since glass ceramics including a light absorbing material to be described later can obtain a three-point bending strength of, for example, 250 MPa or more, sufficiently high strength can be obtained as compared with general glass materials.

As the light absorbing material, for example, a black pigment capable of coloring a ceramic material other than a glass material to black can be used.
Examples of black pigments include metal oxide pigments or composite metal oxide pigments containing at least one metal selected from Cr, Co, Ni, Fe, Mn, and Cu, and titanium represented by TiO _x or TiO _x N _y. And black pigments.
Specific examples of the composite metal oxide pigment include, for example, Co—Fe—Cr black pigment, Cu—Cr—Mn black pigment, Mn—Bi black pigment, Mn—Y black pigment, Fe—Cr. Black pigments, Cr—Cu pigments, and Mn—Fe pigments can be used, and these can be used alone or in combination of two or more.
Among these, Cu-Cr-Mn black pigments, Cr-Cu pigments, and Mn-Fe pigments have high blackness, and in the spacer 24, excellent light absorption characteristics with respect to light in the visible light range can be obtained. Therefore, it is preferable. Here, the blackness is “blackness” and indicates the degree of black.

The 50% particle size (D ₅₀ ) of the light absorbing material is preferably 0.2 μm or more and 15 μm or less.
If the light-absorbing material has a 50% particle size (D ₅₀ ) of less than 0.2 μm, the light-absorbing material is difficult to uniformly disperse in the spacer 24, so that the light is emitted from the side surface direction of the lens unit 12 toward the lens unit 12. The light L1 that is generated cannot be blocked, and the light L2 that generates scattered light in the gap S may not be sufficiently absorbed. For this reason, there is a possibility that the ratio of light other than the convergent light from the lens portions 232 and 222 reaching the light receiving surface of the light receiving element 15 is increased.
On the other hand, if the 50% particle size (D ₅₀ ) of the light absorbing material exceeds 15 μm, it becomes difficult to contain the light absorbing material densely in the spacer 24, and uniform light shielding properties and light absorbing characteristics are obtained in the spacer 24. It becomes difficult.
By setting the 50% particle size (D ₅₀ ) of the light-absorbing material to 0.2 μm or more and 15 μm or less, the spacer 24 can obtain a sufficient light-shielding property and also has sufficient light for the scattered light in the gap S. Absorption characteristics can be obtained. The 50% particle size (D ₅₀ ) of the light absorbing material is more preferably 0.3 μm or more and 7.5 μm or less. In the present specification, the 50% particle size (D ₅₀ ) refers to a value obtained by a particle size measuring apparatus using a laser diffraction / scattering method.

  Hereinafter, glass ceramics will be described. Glass ceramics are those in which ceramic particles are dispersed in a glass matrix as described above.

Glass matrix is, for example, a mole percentage based on oxides, _{SiO 2 57~65%, B 2 O} 3 and 13 to 18%, the CaO 9 to 23% of _Al 2 _{O 3} 3 to 8% that at least one of Na ₂ O and _{K 2} O containing 0.5 to 6% is preferred. In the present specification, “at least one type” means that one type may be used or a combination of two or more types may be used.

SiO ₂ is a glass network former. If SiO ₂ is less than 57%, it is difficult to obtain stable glass, and chemical durability tends to be lowered. From the viewpoint of improving chemical durability, it is preferably 58% or more, more preferably 59% or more, and particularly preferably 60% or more. If it exceeds 65%, the glass melting temperature or the glass transition point (Tg) may be too high, preferably 64% or less, more preferably 63% or less.

B ₂ O ₃ is a glass network former. If B ₂ O ₃ is less than 13%, the glass melting temperature or Tg may be too high, preferably 14% or more, more preferably 15% or more. If it exceeds 18%, it may be difficult to obtain a stable glass or the chemical durability may be lowered, and it is preferably 17% or less, more preferably 16% or less.

  CaO is a component that contributes to stabilization of the glass, reduction of the glass melting temperature, and precipitation of crystals during firing, and may lower the Tg of the glass. If CaO is less than 9%, the glass melting temperature may be too high, preferably 10% or more. When it is desired to easily melt the glass, it is preferably at least 12%, more preferably at least 13%, particularly preferably at least 14%. If it exceeds 23%, the glass may become unstable, preferably 22% or less, more preferably 21% or less, particularly preferably 20% or less, and typically 18% or less.

Al ₂ O ₃ is a component that increases the stability, chemical durability, strength, and the like of glass. If Al ₂ O ₃ is less than 3%, the glass tends to be unstable, preferably 4% or more, more preferably 5% or more. If it exceeds 8%, the glass melting temperature or Tg becomes too high, preferably 7% or less, more preferably 6% or less.

Na ₂ O and K ₂ O are components that lower Tg and contain at least one of them. If the total amount (Na ₂ O + K ₂ O) is less than 0.5%, the glass melting temperature or Tg may be too high, preferably 0.8% or more. If the total amount exceeds 6%, chemical durability, particularly acid resistance, may be lowered. Or there exists a possibility that the electrical property etc. of a sintered body may fall, Preferably it is 5% or less, More preferably, it is 4% or less.

Although it is preferable that a glass matrix consists essentially of the said component, it can contain another component in the range which does not impair the objective of this invention. When other components are contained, the total content is preferably 10% or less. For example, TiO ₂ can be contained for the purpose of reducing the viscosity of the glass melt, and its content is preferably 3% or less. Moreover, ZrO ₂ can be contained for the purpose of improving the stability of the glass, and its content is preferably 3% or less. Further, Nb ₂ O ₅ may be contained for adjusting the refractive index of glass, improving chemical resistance, and adjusting the crystallinity. The content is preferably 10% or less. In addition, it is preferable not to contain lead oxide.

The ceramic particles are typically alumina particles. By including alumina particles, the strength can be increased. The ceramic particles are not limited to alumina particles, and other types of ceramic particles such as SiO ₂ , ZrO ₂ , TiO ₂ , MgO, mullite, AlN, Si ₃ N ₄ , SiC, and forsterite can also be used. Further, a plurality of types of fillers may be mixed and used according to the purpose.

The 50% particle size (D ₅₀ ) of the ceramic particles is preferably 0.1 to ₅ μm. When D ₅₀ is less than 0.1 μm, for example, the ceramic particles may not be uniformly dispersed in the glass matrix, or the ceramic particles are likely to aggregate and handleability is reduced. D ₅₀ is more preferably 0.3 μm or more. D ₅₀ is difficult to obtain a dense sintered body exceeds 5 [mu] m, more preferably at most 3 [mu] m.

It is preferable that glass ceramics contain 40 to 75% of glass matrix and 25 to 60% of ceramic particles in terms of volume percentage.
If the content of the glass matrix is less than 40%, a dense fired product may not be obtained by firing, and the surface smoothness may be impaired because the content of ceramic particles is relatively high. , Preferably 45% or more. Further, if the content of the glass matrix exceeds 75%, the strength may be insufficient, preferably 70% or less, more preferably 65% or less.

FIG. 3 is an enlarged sectional view showing the spacer 24.
In the spacer 24, it is preferable that an angle θ of a smaller one of angles formed by a plane parallel to the end surface of the cylindrical shape and the inner surface of the cylindrical shape is 80 degrees or more. If the angle θ is less than 80 degrees, an excessively small diameter has occurred, and light blocking by the small diameter portion becomes large. The angle θ is more preferably 85 degrees or more.

  Such an angle θ can be achieved by manufacturing the spacer 24 by manufacturing and firing a ceramic green sheet. Specifically, it can be achieved by forming a through hole that becomes a void portion of the spacer 24 by punching at the stage of the ceramic green sheet. In other words, the conventional method of sandblasting or etching a glass wafer gradually decreases the hole diameter in the depth direction of the through-hole, but the ceramic green sheet punching process reduces the hole diameter compared to these. Can be suppressed.

Here, the spacer 24 may be formed by laminating and firing a plurality of ceramic green sheets. In this case, when a plurality of ceramic green sheets are punched one by one and then laminated and fired, a plurality of angles θ exist as shown in FIG. 4 (θ _{1 to} θ _3). ). In such a case, it is preferable that the smallest angle among the angles θ (θ _{1 to} θ ₃ ) is 80 degrees or more.

  In the spacer 24, the height of minute convex portions such as burrs around the cylindrical opening is preferably 15 μm or less. The height of such a convex portion can also be achieved by manufacturing the spacer 24 by manufacturing and firing a ceramic green sheet. Specifically, it can be achieved by forming a through hole that becomes a void portion of the spacer 24 by punching at the stage of the ceramic green sheet.

Hereinafter, a method for manufacturing the spacer 24 will be described.
In the following description, the spacer 24 is made of glass ceramics containing a light absorbing material.

  First, a green sheet composition comprising a green sheet glass powder, a green sheet ceramic powder, and a light absorbing material is prepared.

  The glass powder for green sheets is usually produced by pulverizing glass obtained by a melting method. This glass shall correspond to the glass composition of the glass matrix as described above. The pulverization method may be dry pulverization or wet pulverization. In the case of wet pulverization, it is preferable to use water as a solvent. For pulverization, a pulverizer such as a roll mill, a ball mill, or a jet mill can be used as appropriate. After grinding, the glass is dried and classified as necessary.

  A predetermined green sheet ceramic powder such as alumina powder is added to the green sheet glass powder to obtain a green sheet glass ceramic composition.

  Such a glass-ceramic composition for green sheets and the above-described light-absorbing material are blended so that, for example, the content of the light-absorbing material with respect to the entire composition for green sheets is 2% by volume or more and 20% by volume or less, By mixing, a green sheet composition can be obtained. If the content of the light absorbing material is less than 2% by volume, the spacer 24 cannot sufficiently block the light L1 emitted from the side surface of the lens unit 12 toward the lens unit 12, and is scattered in the gap S. There is a possibility that the light L2 that generates light cannot be sufficiently absorbed.

  On the other hand, if the content of the light absorbing material exceeds 20% by volume, the green sheet composition is difficult to be densely fired, and the strength of the spacer 24 may be reduced, and damage due to external pressure may easily occur. By setting the content of the light absorbing material to 2% by volume or more and 20% by volume or less with respect to the entire green sheet composition, sufficient light shielding properties and light absorbing characteristics can be obtained while maintaining the strength of the spacer 24. it can. For this reason, it is possible to obtain a high-definition image in which the influence of light other than the convergent light by the lens portions 232 and 222 is suppressed. The content of the light absorbing material is preferably 3% by volume or more and 10% by volume or less.

  Further, the green sheet composition and a resin such as polyvinyl butyral and acrylic resin are mixed with a plasticizer such as dibutyl phthalate, dioctyl phthalate, and butyl benzyl phthalate, if necessary.

  Further, a solvent such as toluene, xylene, or butanol is added to form a slurry, and this slurry is formed into a sheet by a doctor blade method or the like on a film of polyethylene terephthalate or the like. The sheet formed into a sheet is dried to remove the solvent to obtain a green sheet (sheet manufacturing process). The thickness of the green sheet can be changed as appropriate, and varies depending on whether only one sheet is used or plural sheets are used, but is preferably 100 to 300 μm from the viewpoint of productivity and the like.

  FIG. 5 is a plan view showing an example of a green sheet. The green sheet 30 has, for example, a quadrangular shape as illustrated. Usually, the green sheet 30 is manufactured in the same size as or larger than various wafers used for manufacturing a wafer level package such as the imaging device 11 in the size after firing. Here, a portion of the green sheet 30 corresponding to a plurality of wafer level packages in the wafer is a region to be the spacer 24. A plurality of such regions are arranged in the vertical and horizontal directions of the green sheet 30 (not shown).

  Through holes are formed in the green sheet 30 by punching to form the through holes serving as the gaps of the spacers 24 (hole forming step). FIG. 6 is a plan view showing the green sheet 30 in which through holes are formed. In the green sheet 30, one through hole 31 is formed in each region to be the spacer 24.

  Note that only one green sheet 30 may be used, or a plurality of green sheets 30 may be stacked. In the case of using a plurality of stacked layers, the through holes 31 may be formed one by one, and then the through holes 31 may be aligned and stacked, or the through holes 31 may be stacked. After the unformed ones are stacked, the through holes 31 may be formed collectively for the entire stacked ones. Usually, since alignment of the through hole 31 is unnecessary, it is preferable to form the through hole 31 after stacking a plurality of sheets.

  The green sheet 30 in which the through holes 31 are formed is cut at unnecessary portions so that, for example, the shape after baking is the same as that of a wafer used for manufacturing a wafer level package. FIG. 7 is a plan view showing an example of the green sheet 30 with unnecessary portions cut. For example, the green sheet 30 is cut into a circular shape so as to have the same shape as various wafers used for manufacturing a wafer level package such as the imaging device 11.

  Thereafter, the green sheet 30 is degreased to decompose and remove the binder and the like, and then fired to sinter the glass ceramic composition (firing step).

  Degreasing can be performed, for example, by holding at a temperature of 500 to 600 ° C. for 1 to 10 hours. When the degreasing temperature is less than 500 ° C. or the degreasing time is less than 1 hour, the binder or the like may not be sufficiently decomposed and removed. If the degreasing temperature is set to about 600 ° C. and the degreasing time is set to about 10 hours, the binder and the like can be sufficiently removed, but if this time is exceeded, productivity and the like may be lowered.

  Firing is performed, for example, by holding at a temperature of 850 to 900 ° C. for 20 to 60 minutes. If the firing temperature is less than 850 ° C. or the firing time is less than 20 minutes, a dense sintered body may not be obtained. If the firing temperature is about 900 ° C. and the firing time is about 60 minutes, a sufficiently dense product can be obtained.

  By such firing, a spacer assembly (spacer wafer) in which a plurality of spacers 24 are combined in a plane can be manufactured. Specifically, a spacer assembly in which a large number of spacers 24 are arranged vertically and horizontally can be manufactured.

  The thickness of the spacer aggregate is not necessarily limited, but is preferably 0.2 to 1.5 mm, and more preferably 0.3 to 1.2 mm. By setting the thickness of the spacer aggregate within the above range, it is possible to obtain the spacer 24 having sufficient strength and excellent light shielding properties.

  The number of spacers 24 in the spacer assembly is not necessarily limited, but is preferably 1000 to 10,000, and more preferably 2000 to 7000. Furthermore, the hole diameter of the through hole in the spacer assembly is not necessarily limited, and varies depending on the number of spacers 24 in the spacer assembly, but is preferably 0.5 to 5.0 mm, more preferably 1.0 to 3.0 mm. . In addition, a hole diameter is taken as the hole diameter in the main surface side with a larger hole diameter, when a hole diameter differs in the front and back surfaces side of a spacer aggregate.

  The spacer aggregate can be made into the spacer 24 by dividing by dicing along the boundary line between the regions to be the spacer 24 (dividing step). The division may be performed by a single spacer assembly or may be performed in a state where other wafers are stacked.

Hereinafter, a method for manufacturing the camera module 10 using the spacer assembly will be described.
First, an imaging device assembly (imaging device wafer) that is an assembly of imaging devices 11 is manufactured, for example, as follows. That is, as shown in FIG. 8, a formed substrate assembly in which the light receiving elements 15 and the electrode pads 17 are formed on an element substrate assembly (element substrate wafer) 411 such as a silicon wafer having a plurality of regions to be the element substrates 13 ( Forming substrate wafer) 41 and a sealing substrate assembly (sealing substrate wafer) 42 such as a glass wafer having a plurality of regions to be the sealing substrate 14, and these are provided on the surface of the sealing substrate assembly 42. Are bonded together by an adhesive layer 16 provided on the substrate.

  In the drawing, a broken line represents a boundary line between the regions. Although not shown, the through-via 19, the wiring layer 21, the solder ball 18, and the like are further formed in the formation substrate assembly 41. As a result, an imaging device assembly (imaging device wafer) that is an assembly of the imaging devices 11 is obtained. The imaging device assembly is divided into individual imaging devices 11 by, for example, dicing at a boundary line between adjacent imaging devices 11.

  On the other hand, a lens unit assembly (lens unit wafer) that is an assembly of lens units 12 is manufactured, for example, as follows. That is, as shown in FIG. 8, a lens element assembly (lens element wafer) 43 having a plurality of regions to be lens elements 22, and a spacer assembly (spacer wafer) 44 having a plurality of regions to be spacers 24, A lens element assembly (lens element wafer) 45 having a plurality of regions to be the lens elements 23 and a filter element assembly (filter element wafer) 46 having a plurality of regions to be the filter elements 25 are prepared.

  The lens element assembly 43 is formed by forming a lens portion 222 from a plastic material or the like in a predetermined region on the surface of a transparent wafer 431 such as a glass wafer. Similarly, the lens element assembly 45 has a lens portion 232 formed of a plastic material or the like in a predetermined region on the surface of a transparent wafer 451 such as a glass wafer. In addition, the filter element aggregate 46 is obtained by forming infrared filters 252 on both main surfaces of a transparent wafer 461 such as a glass wafer.

  The lens element assembly 43, the spacer assembly 44, the lens element assembly 45, and the filter element assembly 46 are bonded together in this order by an adhesive layer (not shown). Thereby, a lens unit aggregate (lens unit wafer) in which a plurality of lens units 12 are joined is obtained. The lens unit aggregate can be divided into individual lens units 12 by dicing at the boundary line between the regions of adjacent lens units 12.

  Thereafter, the lens unit 12 is bonded to the light receiving surface side of the imaging device 11 and, if necessary, the light shielding member 26 is covered except for a part where the light is incident. Thereby, the camera module 10 can be manufactured. The manufacturing method of the camera module 10 is not necessarily limited to the above method. For example, dicing may be performed after the imaging device assembly and the lens unit assembly are bonded together, and the order of stacking and dicing can be changed as appropriate. .

  As described above, the embodiment of the present invention has been described by taking the camera module and the spacer used therein as an example. However, the present invention is not necessarily limited to this, and the gist of the present invention is as necessary. The configuration can be changed as appropriate without departing from the above.

  For example, the wafer level package structure is not necessarily limited to a camera module, and may be another type of module. Further, the wafer level package structure only needs to have at least a wafer level package, and may consist of only a wafer level package. An example of the wafer level package is an electronic component package in which electronic components such as an imaging device and a MEMS device are sealed.

  In addition, the spacer of the embodiment may be used for a wafer level package structure, may be used for various unit parts stacked on the wafer level package, or used for a wafer level package part. May be used. The outer shape of the spacer and the size of the gap in the embodiment can be appropriately changed according to the type of the wafer level package.

  Examples of the wafer level package to which the spacer of the embodiment is applied include an electronic component package in which an electronic component such as an imaging device or a MEMS device is sealed as described above. Such a wafer level package includes an element substrate having an electronic component on the surface, a sealing substrate disposed opposite to the element substrate to seal the electronic component, and the element substrate and the sealing substrate. And a spacer having a spacer which is disposed between the electronic components and hermetically seals the spacer. The spacer of the embodiment is used as such a spacer.

Hereinafter, the present invention will be described in detail with reference to examples.
The present invention is not limited to the following examples.

Example 1
In terms of mol% based on oxide, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K ₂ O is 1%, Na ₂ O. The raw materials were blended and mixed so as to be 2%. The raw material mixture was put in a platinum crucible and melted at 1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. This glass was pulverized with an alumina ball mill for 40 hours to produce a glass powder. In addition, ethyl alcohol was used as a solvent for pulverization.

  Next, this glass powder and alumina powder (manufactured by Showa Denko KK, trade name: AL-45H) were blended so as to have a ratio of 40% by mass of glass powder and 60% by mass of alumina powder, mixed, and glass ceramics. It was set as the composition.

Subsequently, the glass ceramic composition and the black pigment (Cu-Cr-Mn spinel oxide) were 91% by mass (95.5% by volume) of the glass ceramic composition and 9% by mass of the black pigment (4 0.5 volume%) and mixed to prepare a green sheet composition (1).
50 g of this green sheet composition (1) is mixed with 15 g of an organic solvent (toluene, xylene, 2-propanol, 2-butanol mixed at a mass ratio of 4: 2: 2: 1), and a plasticizer (phthalate di- 2-ethylhexyl) 2.5 g, polyvinyl butyral (trade name: PVK # 3000K) 5 g as a binder, and 0.5 g of a dispersant (product name: BYK180, trade name: BYK180) are mixed and mixed. A slurry was prepared.

This slurry was applied onto a PET film by a doctor blade method and dried to produce a green sheet having a shape as shown in FIG.
A number of through holes are formed by punching the green sheet using a punching machine (trade name: MP-8200Z, manufactured by UHT), and a green sheet having through holes as shown in FIG. 6 is formed. Manufactured. Further, the peripheral portion of the green sheet not provided with the through hole was cut to obtain a green sheet molded body having a circular shape as shown in FIG.

  Thereafter, the green sheet is held in a baking furnace at 550 ° C. for 5 hours to decompose and remove the binder resin, and then held at 870 ° C. for 1 hour to be fired to obtain a spacer assembly (spacer wafer). Got. The thickness of the spacer assembly was 0.530 mm. The size of the spacer assembly was 200 mm in diameter, the number of through holes was 4000, and all the through holes had a hole diameter of about 1.5 mm.

(Example 2)
Alumina powder (manufactured by Showa Denko KK, trade name: AL-45H) 81% by mass (81% by volume), blended so that the sintering aid (kaolinite powder) is 10% by mass (14.4% by volume). The ceramic mixture was obtained by mixing.

Next, this ceramic mixture and Fe ₂ O ₃ , CuO, and CO ₂ O ₃ as black pigments, 91% by mass (95% by volume) of the ceramics mixture, and 4% by mass of Fe ₂ O ₃ as the black pigments ( 2.9% by volume), CuO 2% by mass (1.2% by volume), and CO ₂ O ₃ at a ratio of 1.5% by mass (0.9% by volume), mixed, and green sheet A composition (2) was prepared. 50 g of this green sheet composition (2) is mixed with 15 g of an organic solvent (toluene, xylene, 2-propanol, 2-butanol mixed at a mass ratio of 4: 2: 2: 1), and a plasticizer (di-phthalate). A slurry was prepared by blending 2.5 g of 2-ethylhexyl) and polyvinyl butyral as a binder (trade name: BYK180, manufactured by Denka) and mixing them.

This slurry was applied onto a PET film by a doctor blade method and dried to produce a green sheet having a shape as shown in FIG.
A number of through holes are formed by punching the green sheet using a punching machine (trade name: MP-8200Z, manufactured by UHT), and a green sheet having through holes as shown in FIG. 6 is formed. The green sheet was manufactured, and the peripheral portion of the green sheet where the through hole was not provided was cut to obtain a green sheet molded body having a circular shape as shown in FIG.

  Thereafter, the green sheet having the circular shape and the through-hole is held in a baking furnace at 550 ° C. for 5 hours to decompose and remove the binder resin, and then held at 1450 ° C. for 1 hour to be fired to perform spacers. An assembly (spacer wafer) was obtained. The thickness of the spacer assembly was 0.9 mm. The size of the spacer assembly was 200 mm in diameter, the number of through holes was 4000, and the through holes had a hole diameter of about 1.5 mm.

(Comparative Example 1)
In Example 1, a green sheet composition (3) was prepared in the same manner as in Example 1 except that the black pigment was not blended. Using this green sheet composition (3), a green sheet was produced in the same manner as in Example 1, and a green sheet molded product was degreased and fired in the same manner as in Example 1. A spacer assembly (spacer wafer) was obtained. The thickness of the spacer assembly was 0.530 mm. The size of the spacer assembly was 200 mm in diameter, the number of through holes was 4000, and all the through holes had a hole diameter of about 1.5 mm.

  Next, the following evaluation was performed about the spacer aggregate | assembly of Examples 1-2 produced by the said method, and the comparative example 1. FIG.

(Reflectance)
The spacer assemblies of Examples 1 and 2 and Comparative Example 1 were irradiated with visible light in a wavelength region of 400 to 750 nm, and the reflectance was measured using a spectroscope “USB2000” (manufactured by Ocean Optics) and a small integrating sphere. It measured using "ISP-RF" (made by Ocean Optics). As a result of typical reflectance measurement, the reflection spectrum of Example 1 is shown in FIG. The average value of the reflectance in the visible light region obtained as described above is shown in Table 1 below.

(3-point bending strength)
A three-point bending strength test (based on JIS C2141) was performed on the test pieces manufactured in the same manner as the spacer assemblies of Examples 1 and 2 and Comparative Example 1. That is, one side of a test piece is supported at two points, and a load is gradually applied to an intermediate position between the two points on the opposite side to measure the load when the test piece is cut. The three-point bending strength (MPa) was calculated. The bending strength was measured at 30 points to determine an average value (average bending strength).

  In Table 1, the measurement result of the intensity | strength of the spacer assembly of Examples 1-2 and the comparative example 1 is shown.

  As is apparent from FIG. 9 and Table 1, according to the spacer assembly of Examples 1 and 2 made of a ceramic material other than a glass material containing a light absorbing material, a wavelength region of 400 to 800 nm which is a visible light region. Since the average value of the reflectance at 30 is 30% or less, sufficient light shielding properties and light absorption characteristics can be obtained. On the other hand, as is apparent from Table 1, the spacer aggregate of Comparative Example 1 that does not contain a light absorbing material had a high average value of reflectance of 97% in the above wavelength region, and was inferior in light absorption characteristics.

  DESCRIPTION OF SYMBOLS 10 ... Wafer level camera module (wafer level package structure), 11 ... Imaging device (wafer level package), 12 ... Lens unit, 13 ... Element substrate, 14 ... Sealing substrate, 15 ... Light receiving element, 16 ... Adhesive layer, DESCRIPTION OF SYMBOLS 17 ... Electrode pad, 18 ... Solder ball, 19 ... Through-via, 21 ... Wiring layer, 22 ... Lens element, 23 ... Lens element, 24 ... Spacer, 25 ... Filter element, 26 ... Light shielding member, 30 ... Green sheet, 31 ... through holes, 41 ... formed substrate aggregate (formed substrate wafer), 42 ... sealed substrate aggregate (sealed substrate wafer), 43 ... lens element aggregate (lens element wafer), 44 ... spacer aggregate (Spacer wafer), 45 ... lens element assembly (lens element wafer), 46 ... filter element Aggregate (wafer for filter element), 221 ... transparent substrate, 222 ... lens part, 231 ... transparent substrate, 232 ... lens part, 251 ... transparent substrate, 252 ... infrared filter, 411 ... wafer for element substrate, 431 ... transparent wafer 451 ... transparent wafer, 461 ... transparent wafer, S ... gap, L1 ... light from the side of the lens unit 12, L2 ... light that generates scattered light in the gap S

Claims (12)

A spacer for a wafer level package structure,
A spacer comprising a light absorbing material and made of a ceramic material other than a glass material.   The spacer according to claim 1, wherein the spacer is obtained by firing a ceramic green sheet.   The spacer according to claim 1 or 2, wherein a content of the light absorbing material in the mixture is 20% by volume or less.   The spacer according to any one of claims 1 to 3, wherein an average particle diameter of the light absorbing material is 15 µm or less.   The spacer according to any one of claims 1 to 4, wherein a visible light reflectance of the spacer is 30% or less.   The spacer according to claim 1, wherein the ceramic material is glass ceramic.   The spacer according to claim 1, wherein the ceramic material is alumina ceramic.   A spacer assembly comprising a plurality of the spacers according to claim 1 joined together. A wafer level package structure having at least a wafer level package and a spacer for forming a gap inside or outside the wafer level package,
A package structure comprising the spacer according to claim 1 as the spacer.   The wafer level package structure is a wafer level camera module having an imaging device as the wafer level package and a lens unit arranged on a light receiving surface side of the imaging device, and the lens unit has the spacer. The wafer level package structure according to claim 9. A sheet manufacturing process for manufacturing a ceramic green sheet containing a light absorbing material, made of a ceramic material other than a glass material, and having a plurality of regions serving as spacers for a wafer level package structure;
A hole forming step of forming a through hole in the region;
And a firing step of firing the ceramic green sheet to form a spacer aggregate.   Furthermore, the spacer manufacturing method of Claim 11 which has the division | segmentation process which divides | segments the said spacer aggregate | assembly in the boundary line between the said area | regions, and makes it a some spacer.

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